1. Field of the Invention
The invention relates in general to a semiconductor device and a method of fabricating the same, and more particularly to a semiconductor device subjected to a nitridation process and a method of fabricating the same.
2. Description of the Related Art
As the digital era progresses, the demand for data memory medium is increased gradually. Therefore, the trend of the semiconductor technology in fabricating memory medium is continuously developed toward mass production at low cost.
Among data memory medium fabricated by semiconductor technology, non-volatile memory (NVM) which does not need electricity to maintain the data memory status is widely applied. Non-volatile memory can be sorted into one-time programmable memory and multiple-time programmable memory. A one time programmable memory can be exemplified by a basic input/output system (BIOS) or a mask read-only memory (MROM), and a multiple-time programmable memory can be exemplified by a flash memory. In the fabricating process of an one time programmable memory, data is permanently written into the circuit of the memory. Once the memory is complete, the memory can only be read but can not be reprogrammed or erased. As for a multi-time programmable memory, programming, erasing or reading process is performed by providing voltage, that is, data stored in the multiple-time programmable memory can be reprogrammed or erased accordingly. In light of the conveniences of the multiple-time programmable memory, various consumer electronic products now take the multiple-time programmable memory as the medium for storage.
Commonly, a metal-oxide-semiconductor (MOS) structure including a gate stack, a charge storage layer and a base is used in the non-volatile memory cell. The base has a drain region and a source region at two sides of the gate stack. The carriers are accumulated in or removed from the charge storage layer by a strong electric field generated by applying different voltages to the gate, the drain, the source and the base of the memory, and thus data stored in the memory is changed. During erasing, carriers are removed from the charge trapping layer; during programming, carriers are accumulated in the charge trapping layer.
In the conventional non-volatile memory, the circuits of a cell region and a peripheral region are integrated. A logic device, such as a complementary metal oxide semiconductor (CMOS), is generally disposed in the peripheral region. However, due to the highly sophisticated fabricating process of the cell and the incompatibility of the fabricating processes of the cell and the CMOS, it is difficult to simplify the fabricating steps of the memory. Also, the fabricating time and cost can not be reduced as well.